Process for production of self-baking electrodes



July 31, 192s. '13579284 D J. WESTLY PROCESSFOR PRODUCTION OF SELFBAKING 'LECTRODES Filed Jan. 5, 1925 gwen/tot 61H01 u e 14 ing PatentedJuly 31, 1928.

UNITED STATES PATENT OFFICE.'

.TENS WESTLY, F CHRISTIANSAND, NORWAY., ASSIGNOR TO D'ET NORSXEAKTIEHEL- Sm FOB ELEKTROKEMISK INDUSTRI OIF NORWAY, 0F OSLO, NORWAY.

:PROCESS FOB PRODUCTION 0F SELF-BARING ELECTBODES.

appumian ma January 5, 1925, serial No. 712, and in Norway January 17,1924.

`The present application relates to selfbakelectrodes provided withmetallic man.- tes, that is electrodes which are baked 1n t e object ofthe invention is a process which -makes 1t possible to avoidintroductionv of detrimental materlal from the mantle into the furnace.Such selfbaking electrodes are 'described in U. S. Patentv No. 1,440,724

wherein is stated that one of the functions of the mantle is to transmitthe current to the electrode. For that purpose it is often provided'withinternal ribs or extensions pro- 'ccting into the electrode mass andfacilitatmg the paage of the current, as these ribs maintain anexcellent contact with the mass. Generally both the mantle and the ribsare made of iron and the ribs form a part of the plate from which themantle is made.

The iron melts during the process and enters into the product of thefurnace. In special cases'the mantle may also be made of. other metals,as for instance copper or aluminium. These metals, however, have thedrawback that their meltin e point is considerably lower than that of1ron (respectively 150 G. and 660 0.). This drawback is especiallynoticeable with aluminium, whose melting point is so low that theelectrode at 'that temperature is not yet so well baked that it has evenapproximately reached'its normal electric conductivity. If both mantleand ribs are made of aluminium there will be a greater loss of voltavein the electrode than that normally found when employing iron. I have,however, found that the loss of voltage may be reduced to a considerableextent by making the ribs of comparatively f great thlckness. They willthen allow the electric currentto pass through them without being heatedto' any considerable extent and they will not melt until thesurroundingr mass-has reached a temperature corresponding to theirmelting point.

The ribs may be arran ed horizontally or verticall or at any ang e' withhorizontal plane. urther they may be partly horizontal or vertical andartly inclined. A s al advantage is obtained if the internal ribs slopedownwardly into the electrode mass.

If the metal of the ribs melts it will then not run out of theelectrode, but will remain in a pocket in the electrode ma and maintainthe connection with the non-molten part furnace in which they are usedand they of the mantle. In this .way it is possible to eilect passage ofthe current from metal to electrode at temperatures ranging above theFig. 2 is a cross section of the same electrode the numerals indicatingthe same parts as in Fig. 1. A

Another modification of my invention con. sists in reducing the size ofthe ribs So much that the amount of metal which passes into the furnaceon account of the ribs is unimportant as compared with the amount of theproduct and in such cases the ribs may be made of iron or other materialdetrimental to the product even if this cannot be permitted -in thefurnace in larger amounts. This especially applies to furnaces for, theproduction of aluminium. The mantle which is allowed to pass into thebath should of course in such cases not be made of iron,

but of a non-detrimental metal such as aluminium and care should then betakento su ply the electric current to the ribs in a sa e manner; forinstance by means of a clamping arrangement attached to the mant e or toexternal prolongations of the ribs as described and claimed/in mycopending application Serial No. 711.

It is of course advisable in the present case to reduce the si'ze of theiron ribs to the minimum possible in order to introduce the leastpossible amount of the detrimental metal into the furnace. This may beeffected by placing the electrode Aholder as farv as possible on bakedelectrode carbon whereby as much as possible of the current will assdirectly over to the electrode under the ho der without passing throughthe ribs. In prac- -1ron melts at about 850 C., that is about n0 200 C.higher than pure aluminium. The alloy is therefore` better adapted foruse as rib material than aluminium. It is, however, dificult to roll forWhich reason it will be preferable to make the ribs by casting.

What I claim'as new and desire to secure by Letters Patent of the UnitedStates is:

1. A selfbaking electrode having a mantle of one composition,non-detrimental to the processin connection with which the electrode isbeing used, and internally projccting ribs of another compositionattached to said mantle.

2. A selfbaking electrode having a. mantle of one composition,non-detrimental to the proce-ss in connection with which the electrodeis being used, and internal ribs composed of a comparatively ditlicultlyfusible metal and attached to said mantle. v

3. A selfbaking electrode having a mantle of one composition,non-'detrimental to the process in connection with which the electrodeis being used, and internal ribs composed of a comparatively dicultlyfusible metal attached to said mantle in combination with an electrodeholder attached to a baked part of the'electrode..

4. A selfbaking electrode having an aluminum mantle and internal ribscomposed of a comparatively difficulty fusible metal attached thereto.

5. A selfbaking electrode having an aluminum mantle and internal ribs ofdiflicultly fusible metal attached thereto, said ribs being of suchsmall size that they Will not introduce a detrimental amount of suchmetal into the furnace product.

6. A Selfbaking electrode having an aluminum mantle and internalaluminum ribs attached thereto, said ribs being of such dimensions as toavoid' any considerable heatl ing due to the passage of electriccurrent.

A se-lfbaling electrode having an aluminum mantle and internal aluminumribs attached thereto, said ribs being of such dimensions as to avoidany considerable heating by the electric current passing therethrough,said ribs being disposed at an angle With the horizontal plane.

8. A selfbaking electrode having an aluminum mantle and internalaluminum ribs att-ached thereto, said ribs being of such dimensions asto avoid any considerable heating by the electric current passingtherethrough, said ribs sloping downwardly into the elect-rode.

9. A self-baking electrode having an aluminum mantle, and internallyprojecting ribs of another composition attached to said mantle.

J EN S WESTLY.

